Acquired immune deficiency syndrome (AIDS), a recently described disease affecting primarily homosexuals and intravenous drug abusers, has generated considerable interest. At the National Institutes of Health we have performed autopsies on 18 patients with AIDS. General necropsy findings in the first 10 patients recently was reported. This report focuses specifically on cardiac findings in the 18 patients. Of the 18 patients, 5 (28%) had abnormalities in the heart and in each they consisted of focal deposits of Kaposi's sarcoma (KS). All 5 patients were white men aged 26-52 years (mean 41). The initial manifestation of AIDS in each was a dermal lesion which on biopsy was KS. The interval from the appearance of the dermal KS to death ranged from 6-22 months (mean 11). During life, no patient had symptoms attributable to cardiac dysfunction. Electrocardiograms recorded during the last 3.5 months of life were normal in all 5 patients. All 5 had normal sized hearts by chest roentgenogram and each had normal sized hearts at necropsy. At necropsy, small, focal, hemorrhagic areas involved subepicardial adipose tissue adjacent to greater than or equal to 1 major coronary arteries in all 5 patients. The KS was similar histologically to that seen in other anatomic sites, and was typical of what has been previously described. Three patients also had deposits of KS in the adventitia of ascending aorta, and 1 of them also had KS in the adventitia of the pulmonary trunk. The myocardium and endocardium was free of KS. The lumens of the coronary arteries were normal in 4 patients, and 1 major coronary artery, not involved by KS, was narrowed 51-75% in cross-sectional area by atherosclerotic plaque in 1 patient. No infectious complications of AIDS were identified histologically. Toxoplasma gondii, however, was isolated in 1 patient from mice injected intraperitoneally with a homogenate of myocardium.